US3666409A

US3666409A - Method of stabilizing sodium hydrosulfite

Info

Publication number: US3666409A
Application number: US852891A
Authority: US
Inventors: Yoshio Yoshikawa; Yasuhiro Sakai
Original assignee: Mitsubishi Edogawa Kagaku KK
Current assignee: Mitsubishi Edogawa Kagaku KK
Priority date: 1969-01-31
Filing date: 1969-08-25
Publication date: 1972-05-30
Anticipated expiration: 1989-05-30
Also published as: GB1262560A; DE1943459A1; FR2029738A1; DE1943459B2

Abstract

SODIUM HYDROSULFITE IS STABILIZED BY USING AN ALIPHATIC AMINE CONTAINING FIVE OR MORE CARBON ATOMS.

Description

3,666,409 METHOD OF STABILIZIN G SODIUM HYDROSULFITE Yoshio Yoshikawa and Yasuhiro Sakai, Tokyo, Japan, assignors to Mitsubishi Edogawa Kagaku Kabushlki Kaisha, Tokyo, Japan No Drawing. Filed Aug. 25, 1969, Ser. No. 852,891 Claims priority, application Japan, Jan. 31, 1969, 44/6,626 Int. Cl. B01d 17/66 US. Cl. 23116 22 Claims ABSTRACT OF THE DISCLOSURE Sodium hydrosulfite is stabilized by using an aliphatic amine containing five or more carbon atoms.

This invention relates to a method of stabilizing sodium hydrosulfite, particularly an improvement in stability of sodium hydrosulfite when allowed to stand in air, and more particularly a method of stabilizing sodium hydrosulfite by adding an amine thereto.

Sodium hydrosulfite is water-soluble and a strong reducing agent and is useful as dyeing assistant.

Since sodium hydrosulfite is highly reductive, sodium hydrosulfite easily reacts with oxygen in the presence of moisture as follows:

Nagszo4 02'' Na 2SO3 and further may be decomposed by oxidation according to other reaction mechanism.

When sodium hydrosulfite is stored in a state completely free from moisture and oxygen, sodium hydrosulfite is fairly stable and only a slight change is observed even after one year storage.

However, in practical use it is very diflicult to handle sodium hydrosulfite without contacting with moisture and air. It often occurs that sodium hydrosulfite taken out of a container is handled for weighing or other purposes in an atmosphere of high humidity in a dyeing factory.

Even if a lid is put on the container immediately after the lid is taken off for taking out sodium hydrosulfite, it is inevitable that moisture and air enter the container to some extent. It is common sense in handling sodium hydrosulfite to use sodium hydrosulfite in a container as soon as possible once the container is opened. However, it is needless to say that sodium hydrosulfite product of high stability when left in air is more preferable in handling.

It is considered that the stability of sodium hydrosulfite increases when the surface of the hydrosulfite is completely covered with a hydrophobic material, but there occurs a disadvantage that the water-solubility of the hydrosulfite is hindered.

It is an object of this invention to improve the stability of sodium hydrosulfite when left in air without lowering the water solubility and reducing power.

The present inventors have now found that the stability of sodium hydrosulfite is remarkably improved by adding an aliphatic amine having five or more carbon atoms thereto.

It is well known that sodium hydrosulfite is unstable in an acidic state and produces acidic substances as the result of the self-decomposition.

In view of such properties of sodium hydrosulfite, conventional stabilizers for sodium hydrosulfite are alkaline substances such as sodium carbonate, sodium silicate, sodium phosphate, hexamine and the like.

In view of such prior arts, it is considered that an amine may be used in place of the alkaline substance for the 3,666,409 Patented May 30, 1972 purpose of increasing the stability, but the characteristic feature of this invention does not reside in a simple addition of an amine, but the selection of such a particular amine is very important which has at least five or more, preferably 8 or more, carbon atoms, in other words, a group which is hydrophobic to some extent. The mechanism of this invention is considered as follows.

The surface of sodium hydrosulfite crystal is slightly more acidic than the inside of the crystal due to the selfdecomposition.

The added amine bonds to the acidic part and is adsorbed on the surface of sodium hydrosulfite with the hydrophobic group directed outside. Thus, the acidity of the surface of sodium hydrosulfite is neutralized and simultaneously the surface of the hydrosulfite is covered with hydrophobic group. As the bonding manner, coordinate bond is also considered, but anyhow the nitrogen atom participates in the bonding so that the surface of sodium hydrosulfite is covered with hydrophobic group also in this case.

In this manner, the addition of the amine according to this invention results in the decrease of hydrophilic property of surface of sodium hydrosulfite as compared with untreated sodium hydrosulfite, remarkable improvement in stability when left in air and no hindrance in watersolubility and reducing power.

The amine used in this invention is an aliphatic amine having at least five carbon atoms. Generally, the total number of carbon atoms ranges from 5 to 40, preferred with 8 to 20.

The amine may be used in single state or as a mixture of two or more amines. As examples of the amine used according to this invention, there may be mentioned aliphatic primary amine such as amylamine, hexylamine, octylarnine, decylamine, dodecylamine, tetradecylamine, cetylamine, stearylamine, docosyl amine, oleylamine, laurylamine and the like, aliphatic secondary amine such as methyl octyl amine, propyl lauryl amine, methyl oleylamine, dioctyl amine, distearyl amine and the like, aliphatic tertiary amine such as dimethyl octyl amine, dimethyl lauryl amine, dimethyl stearyl amine, dimethyl docosyl amine and the like, quaternary ammonium salt such as octyl trimethyl ammonium chloride and the like, and alkyl substituted diamine such as N-octyl ethylene diamine, N-stearyl propylenediamine and the like.

The amine may be added in various ways. For example, the amine is dissolved in a solvent and sodium hydrosulfide crystal is immersed in the resulting amine solution, or a solvent containing an amine is sprayed on the surface of crystal. One of the most practical methods is that, upon alcohol washing in the production process of sodium hydrosulfite, the washing is carried out by using a washing liquid containing the amine of this invention, and then the sodium hydrosulfite crystal is dried under reduced pressure according to a conventional method.

The amount of amine to be added varies depending upon the kind of amine. Usually 0.01 to 0.2% of amine on the basis of the amount of sodium hydrosulfite is used and 0.03 to 0.1% is particularly preferable.

The following examples are given for illustration of this invention, but not for limitation. The parts are by weight in the following.

EXAMPLE 1 A slurry containing sodium hydrosulfite 500 parts is filtered and the filter cake is washed with 500 parts of methanol containing an amine, and then the cake is sufiiciently separated from the liquid by pressure filtration followed by vacuum drying. The resulting solid matter is allowed to stand in air having humidity over The solid matter thus left in humid air is compared with that not left in the humid air and the comparison result is shown in the following table.

Purity, percent Amount Before 01 added opening amine, the After After After Added amine percent container 7 hours hours 24 hours None 93. 77. 12 61. 75 45. 80 Dimethylstearylamine 0. 03 93. 08 91. 78 83. 40 78. 50 Distearylamme 0. 03 92. 85 87. 95 80. 25 73. 75 Oetylamine 0. 1 93. 41 88. 95 81. 45 75. 82 Long chain alkyl trimethyl ammonium chloride (Quateramine DSGP, trade name) O. 05 93. 38 85. 57 76. 32 70. 28 N-oleyl-l,3-propylenediamine.

(DIAM 11C, trade name). 0.05 90. 92 74.85

EXAMPLE 2 11. A method of stabilizing sodium hydrosulfite ac- Crystal of hydrosulfite (500 parts) is placed in a fluidizing dryer and fluidized in nitrogen flow, and 0.25 part of octylamine is sprayed thereto. The resulting hydrosulfite which has absorbed the octylamine is allowed to stand together with the samples as shown in Example 1 above. The result is shown below.

What is claimed is:

1. A method of stabilizing solid sodium hydrosulfite which comprises coating the exterior surface of said hydrosulfite with an aliphatic amine containing five or more carbon atoms.

2. A method of stabilizing solid sodium hydrosulfite which comprises coating the exterior surface of said hydrosulfite with an aliphatic amine having five to forty carbon atoms.

3. A method of stabilizing solid sodium hydrosulfite which comprises coating the exterior surface of said hydrosulfite with an aliphatic amine having 8 to 20 carbon atoms.

4. A method of stabilizing sodium hydrosulfite according to claim 1 in which the aliphatic amine is a primary amine.

5. A method of stabilizing sodium hydrosulfite according to claim 1 in which the aliphatic amine is a secondary amine.

6. A method of stabilizing sodium hydrosulfite according to claim i]. in which the aliphatic amine is a tertiary amine.

7. A method of stabilizing sodium hydrosulfite according to claim 1 in which the aliphatic amine is quaternary amine.

8. A method of stabilizing sodium hydrosulfite according to claim 1 in which the aliphatic amine is an alkyl substituted diamine.

=9. A method of stabilizing sodium hydrosulfite according to claim 4 in which the primary amine is selected from the group consisting of amylamine, hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, cetylamine, stearylamine, docosylamine, oleylamine and laurylamine.

10. A method of stabilizing sodium hydrosulfite according to claim 5 in which the secondary amine is selected from the group consisting of methyl octyl amine, propyl lauryl amine, methyl oleyl amine, dioctyl amine and distearyl amine.

cording to claim 6 in which the tertiary is amine selected from the group consisting of dimethyl octyl amine, dimethyl lauryl amine, dimethyl stearyl amine and dimethyl docosyl amine.

12. A method of stabilizing sodium hydrosulfite according to claim 7 which the quaternary amine is octyl trimethyl ammonium chloride.

13. A method of stabilizing sodium hydrosulfite according to claim 8 in which the alkyl substituted diamine is selected from the group consisting of N-octyl ethylene diamine and N-stearyl propylenediamine.

14. A stable sodium hydrosulfite composition comprising solid sodium hydrosulfite particles, the external surfaces of which are substantially coated with an aliphatic amine containing at least five carbon atoms.

215. The composition of claim 14 wherein the aliphatic amine is selected from the group consisting of primary, secondary, and tertiary amines containing at least five carbon atoms.

'16. The composition of claim 14 wherein the amine is a quaternary ammonium salt.

17. The composition of claim 15 wherein the amine is an alkyl substituted diamine.

18. The composition of claim 15 wherein the primary amine is selected from the group consisting of amylamine, hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, cetylamine, stearylamine, docosylamine, oleylamine and laurylamine.

19. The composition of claim 15 wherein the secondary amine is selected from the group consisting of methyl octylamine, propyl lauryl amine, dimethyl stearyl amine and dimethyl docosylamine.

20. The composition of claim 14 wherein the amine is present in an amount equal to 0.01 to 0.2% based on the amount of sodium hydrosulfite present.

21. The composition of claim 17 wherein the alkyl substituted amine is selected from the group consisting of N-octyl ethylenediamine and N-stearyl propylenediamine.

22. The composition of claim 16 wherein the quaternary ammonium salt is octyl trimethyl ammonium chloride.

References Cited UNITED STATES PATENTS 861,218 7/1907 Majert -23Il6 FOREIGN PATENTS 846,052 3/1955 Canada 23-1 16 EARL C. THOMAS, Primary Examiner US. Cl. X.R. 252--l88